Generally most of the ex-heroin addicts will evolve into social drinkers who will not have any problem with alcohol. Many ex-alcoholics replace marijuana for alcohol. Any reasonable treatment program which teaches that moving from a very harmful drug to a less harmful drug is a move in the correct direction and a good harm reduction strategy. This is known as cross addiction and it is completely a myth (fictitious story).

The myths are, being addicted to one drug will not make a person addicted to other unrelated drugs and use of an unrelated drug will not consequently make a person go back to drug of their choice. If these were true then each drug counselor who puffed a cigarette or had a sip of coffee would promptly be back using heroin or any other unrelated drugs. Although cross-addiction is a myth, there is a circumstance called cross-tolerance which exists and that people who exercises harm reduction must be aware of it.

Cross-tolerance means, when a person develops a tolerance to a drug, then he or she will also have a tolerance to similarly related drugs but not to completely towards dissimilar drugs. For instance, Valium, Librium, Xanax, Ativan and Klonopin are all closely related drugs that corresponds to the benzodiazepine family of drugs. All these drugs will influence GABA receptors in brain. If a person gets addicted to any one of these benzodiazepines then he or she can substitute any other drug of this category as there is cross-tolerance. But, heroin should not be substituted for Valium as heroin will not affect the GABA receptor. Cross tolerance between heroin and Valium is absent.